I've seen the photo in this morning papers in the Midwest. I clipped the photo to post on the work bulletin board. I can tell you immediately without a second thought that is failure is due to erection problems.
To qualify my statement I've more than 20 years on construction and design of heavy highway infrastructure. I've worked on many projects just like this one.
This is not an error on the part of a designer who didn't check girder stresses before the concrete slab was placed.
Where, pray tell, is the lateral bracing?! AASHTO requires designers, like it or not, to place cross-frames on 25' centers, needed or not. When I was a construction inspector (many, many years ago), the contractor was either required to devise a bracing scheme to tie off a girder or use the final cross-frames to tie it off. Moreover, most contractors I've worked with would not unhook the crane even though the its the end of the day and the pick was completed. If the girder wasn't braced, no one was going home until it was.
In the photo that I have, the splice is visible and the different sizes in top flange are also noticible. I would expect the section with the larger top flange to be placed over some intermediate support, in which case, would have smaller cross-frame spacing due to bracing requirements. Many state DOTs do not allow for a full composite section in the area over the pier (negative moment region) thereby not allowing for a positive mechanical anchorage for stability calcs. Moreover, the compression flange is on the bottom where it is not braced by the slab.
In my opinion, this was the work of a unknowledgeble contractor and, if the specifications were written like many others, also the fault of the inspector.
I hope a valuable lesson was learned...it certainly cost someone dearly...
Regards,
Qshake
![[pipe] [pipe] [pipe]](/data/assets/smilies/pipe.gif)
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.